To put what these Windows users are doing in perspective, Windows users are holding onto an OS that was released at the same time as OS X 10.6, and not only doing it, but demanding that developers support this version. If you asked any Cocoa developer to support Snow Leopard, they'd laugh you out of the room.
Your blame is misplaced, these Windows users are doing nothing wrong. Microsoft did terrible releases for years, and is trying to recover from that mistake in a terrible way.
You miss the fact that Windows 8 was such a botch job that most of us didn't start upgrading until Windows 8.1 - and this isn't just end users, but a hell of a lot of IT professionals. This never occurred on OS X.
So what exactly do windows 7 users call in about? Is that because there is some major API difference between 7 and 8 or is does it represent people who buy computers less often?
Windows 7 doesn't have a notifications / toast API which means we have to implement notifications ourselves. It also lets you turn off desktop composition and throw the UI into a completely different rendering path, which Electron doesn't support properly, so we then have to implement notifications again in a fallback software rendering only way. It also doesn't have a spellchecking API, so we get to ship Hunspell in-box and deal with updating dictionaries, the list goes on and on